Abstract: Objective To establish an infant rat model of irritable bowel syndrome with “integrative methods”，and test its visceral sensitivity by two different ways. Methods Sixteen SD neonatal rats were divided into model and control group randomly. The model was established by separated from mother rat，binded up mildly and intrarectal administration of mustard oil and so on; the control group didn’t intervene. After the intervention, let the rats have a rest for 2 weeks. The threshold of abdominal withdrawal reflex (AWR) was evaluated during rectal distension by self-made dilator in different tensions, and the changes of rectal sensitivity were identified by the abdominal electrical activity measured at postnatal 30 days. At last pathological changes of the rectal mucosa was measured. At the beginning of intervention, the two groups’ feces were scored according to the Bristol pattern, collected the feces and measured their wet and dried weights. Results The model group showed a significant decrease (P＜0.01) in the volume threshold of abdominal withdral reflex during rectal distension; there was a significant increase of abdominal electrical activity responding to different distension pressure compared with control rats (P＜0.01). The colon’s pathological changes had no significant difference in the two groups. The feces of model group were mostly soft mass or muddy, Bristol Scores was 5.3 土 0.8; which of control group were delicately sausage or mass, Bristol Scores was 3.6 土 0.5，the difference was significant in the two groups. The wet and dried weights of the model ’s feces were 10.8 ±1.2、 3.2 士 0.4 g respectively, and the control’s were 5.4 土 0.3、3.6 土 0.7 g respectively, there was significant difference in the two groups，wet weights(P＜0.05). Conclusions The “integrative” methods (concluded to separation from mother、mechanism fetter and chronic rectal irritation with mustard oil) to the infant rats may establish the children’s irritable bowel syndrome model，of which mechanism is visceral hypersensitivity possibly.

Key words: Irritable bowel syndrome, Visceral hypersensitivity, Rectal distension, Abdominal electrical activity